Hair styling or hair setting compositions are widely used by consumers in the cosmetic industry to retain a particular shape or style of the hair. Hair styling compositions can assist in manipulating or styling the hair, providing temporary benefits in holding the shape of the hairstyle (fixing) and/or maintaining the shine or appearance (grooming, restyling) of the hair, e.g., in the evening, during the day, between hair washing periods, or between subsequent hair setting procedures.
Hair styling compositions also can be subjectively evaluated, e.g., by visual and tactile sensory methods (e.g., by visual examination and touching) for characteristics such as appearance (shine, cleanliness, naturalness of appearance and texture), feel (stiffness, tackiness, softness), curl memory (bounce, and restylability), ease of combing and brushing the hair, residue (flaking), static, smoothness, and the like. Also of importance are the aesthetic characteristics and appearance provided by hair styling compositions before, during, and after application to hair. Preferably, the product viscosity should be non-runny to avoid dripping during application. The product should be easy to spread, have a smooth texture, a non-tacky feel, and be able to dry relatively quickly on the hair.
However, hair is often subjected to a wide variety of stresses and treatments that can cause damage to the hair. These include shampooing, rinsing, drying, heating, combing, styling (such as relaxing or straightening), penning, bleaching, coloring, exposure to the elements, thermo processes, and the like. Such stresses can leave the hair in a dry, rough, lusterless, or frizzy condition, which can be caused, e.g., by repeated abrasion of the hair surface and removal of the hair's natural oils and other natural conditioning and moisturizing components. Additionally, hair is often subjected to weather-related stresses, e.g., sunlight, wind, and changes in temperature and humidity, which can cause hair damaged and other conditions considered by consumers to be cosmetically undesirable. Such stresses are detrimental to the hair fiber, and often result in decreased hair fiber strength.
Hair-setting compositions that include one or more hair-setting polymers to impart styling and/or fixative properties have been disclosed. For example, U.S. Pat. No. 4,713,236 describes compositions that include amine-containing polymers and copolymers that contain a primary pendant amine group, for imparting conditioning properties to hair. U.S. Pat. Nos. 5,478,553 and 5,632,977 describe hair fixative compositions containing polymeric n-vinyl formamide and methods of treating hair. U.S. Published Patent Application No. 2007/0110690 describes a process for inhibiting hair from becoming frizzy that involves contacting hair with anionic silicone and with polyvinylamine. However, such conventional hair styling methods do not necessarily promote hair fiber strength, particularly in hair that has been damage as a result of exposure to the stresses discussed above.
Accordingly, there is a need for methods of hair styling that serve to increase hair strength, preferably while maintaining desirable subjective properties, e.g., smooth texture, curl memory, bounce, naturalness of appearance, etc. The present invention provides such methods.